In recent years, along with performance improvement, an ink-jet printer has been used in various fields. A photo print is one of them, and its speed and high image quality have reached a level comparable to a conventional silver halide photo. On the other hand, there is a problem of image fastness left in the field of the ink-jet as well as that of the silver halide photo, wherein a color fading in the image occurs during preservation of the image due to environmental factors existing in nature (for example, gas, light, heat, water, and the like).
Currently, discussion exists over the fastness evaluation standard of a digital photo image including the ink-jet image in ISO (International Organization for Standardization) for the purpose of estimating the image fastness. The subject of the discussion includes new standards of, water resistance, moisture resistance, gas resistance, heat resistance (dark place preservation), room light resistance, outdoor weather resistance, and End Point. Among them, an ozone test is taken up as an evaluation method for the gas resistance, and many reports about the ozone test have been made. However, various gas types exist in the real environment, in addition to ozone. Although there is a fear of the influence of these gas types on the gas resistance of the image, there are not many tests performed in combination of the gas types in the real environment other than ozone.
As the test performed in combination of the gas types in the real environment other than ozone, for example, an image weather resistance test method has been disclosed (Japanese Patent Application Laid-Open No. 2004-170403). This method is featured by comprising a step of setting an image in a mixed gas atmosphere, the mixed gas containing ozone and at least one kind of gas other than ozone and another step of irradiating a predetermined amount of light having a predetermined wavelength on the image in the mixed gas atmosphere.
Further, there is a disclosure about a recorded matter having a nonvolatile liquid portion that does not dissolve a color material such as silicone oil (Japanese Patent Application Laid-Open No. 2003-118228) In this disclosure, a gas resistance test using the mixed gas has been performed.
As described above, the ozone test has mainly been performed as an evaluation test method of the gas resistance. However, various gas types exist in the real environment, in addition to ozone, so that it was not necessarily possible to accurately simulate an image degradation degree in the real environment with the ozone test. Further, improvement in the weather resistance of the ink-jet photo image of recent years makes it difficult to perform a real environmental test in terms of development schedule. Thus, the importance of a simulation technique as a means for verifying the gas resistance is increasingly growing.
Further, the gas resistance evaluation method using the mixed gas also cannot accurately simulate an image degradation degree in room environment where the ink-jet image, silver halide photo image, and the like are mainly preserved. Thus, there has been a need of proposing a simple gas resistance evaluation test method for image that can accurately simulate the degree of image degradation in room environment.
The above-mentioned invention disclosed in Japanese Patent Application Laid-Open No. 2004-17043 sees about not only the influence of gas, but also the influence of light. However, an image is not always preserved in the light but may be preserved in a dark place such as a closet or a dark room in some cases. In such cases, there is no need to take the influence of light into consideration. Further, the apparatus used in that invention is very expensive, so that a simple gas resistance evaluation test method for image has been demanded.
The gas resistance test disclosed in Japanese Patent Application Laid-Open No. 2003-118228 is not an evaluation method for a color material, but for silicone oil. Therefore, the test condition disclosed is not related to the evaluation method that the present invention intends to provide at all, and it is impossible to find out the gas resistance test method for image that accurately simulated the degree of image degradation in room environment. Therefore, the simple gas resistance evaluation test method for image that can accurately simulate the degree of image degradation in room environment has still been demanded.
Further, in conventional gas resistance tests, including the above patent document, a constant amount of gas is allowed to flow in a tank. However, the examination by the present inventors reveals that gas concentration on the surface of the image sample to be examined in the present invention varies from part to part even within the single tank, so that a gap between the result of this test and that of the real environmental test may be caused. This problem needs to be solved.